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Journal of Neuroinflammation Jun 2024Traumatic brain injury (TBI) is a significant risk factor for Alzheimer's disease (AD), and accumulating evidence supports a role for adaptive immune B and T cells in...
Traumatic brain injury alters the effects of class II invariant peptide (CLIP) antagonism on chronic meningeal CLIP + B cells, neuropathology, and neurobehavioral impairment in 5xFAD mice.
BACKGROUND
Traumatic brain injury (TBI) is a significant risk factor for Alzheimer's disease (AD), and accumulating evidence supports a role for adaptive immune B and T cells in both TBI and AD pathogenesis. We previously identified B cell and major histocompatibility complex class II (MHCII)-associated invariant chain peptide (CLIP)-positive B cell expansion after TBI. We also showed that antagonizing CLIP binding to the antigen presenting groove of MHCII after TBI acutely reduced CLIP + splenic B cells and was neuroprotective. The current study investigated the chronic effects of antagonizing CLIP in the 5xFAD Alzheimer's mouse model, with and without TBI.
METHODS
12-week-old male wild type (WT) and 5xFAD mice were administered either CLIP antagonist peptide (CAP) or vehicle, once at 30 min after either sham or a lateral fluid percussion injury (FPI). Analyses included flow cytometric analysis of immune cells in dural meninges and spleen, histopathological analysis of the brain, magnetic resonance diffusion tensor imaging, cerebrovascular analysis, and assessment of motor and neurobehavioral function over the ensuing 6 months.
RESULTS
9-month-old 5xFAD mice had significantly more CLIP + B cells in the meninges compared to age-matched WT mice. A one-time treatment with CAP significantly reduced this population in 5xFAD mice. Importantly, CAP also improved some of the immune, histopathological, and neurobehavioral impairments in 5xFAD mice over the ensuing six months. Although FPI did not further elevate meningeal CLIP + B cells, it did negate the ability of CAP to reduce meningeal CLIP + B cells in the 5xFAD mice. FPI at 3 months of age exacerbated some aspects of AD pathology in 5xFAD mice, including further reducing hippocampal neurogenesis, increasing plaque deposition in CA3, altering microgliosis, and disrupting the cerebrovascular structure. CAP treatment after injury ameliorated some but not all of these FPI effects.
Topics: Animals; Mice; Mice, Transgenic; Male; Brain Injuries, Traumatic; Histocompatibility Antigens Class II; Antigens, Differentiation, B-Lymphocyte; B-Lymphocytes; Meninges; Amyloid beta-Protein Precursor; Alzheimer Disease; Humans; Disease Models, Animal; Presenilin-1; Mice, Inbred C57BL
PubMed: 38937750
DOI: 10.1186/s12974-024-03146-z -
Genes Jun 2024Brain lipid homeostasis is an absolute requirement for proper functionality of nerve cells and neurological performance. Current evidence demonstrates that lipid...
Multifactor Analyses of Frontal Cortex Lipids in the APP/PS1 Model of Familial Alzheimer's Disease Reveal Anomalies in Responses to Dietary n-3 PUFA and Estrogenic Treatments.
Brain lipid homeostasis is an absolute requirement for proper functionality of nerve cells and neurological performance. Current evidence demonstrates that lipid alterations are linked to neurodegenerative diseases, especially Alzheimer's disease (AD). The complexity of the brain lipidome and its metabolic regulation has hampered the identification of critical processes associated with the onset and progression of AD. While most experimental studies have focused on the effects of known factors on the development of pathological hallmarks in AD, e.g., amyloid deposition, tau protein and neurofibrillary tangles, neuroinflammation, etc., studies addressing the causative effects of lipid alterations remain largely unexplored. In the present study, we have used a multifactor approach combining diets containing different amounts of polyunsaturated fatty acids (PUFAs), estrogen availabilities, and genetic backgrounds, i.e., wild type (WT) and APP/PS1 (FAD), to analyze the lipid phenotype of the frontal cortex in middle-aged female mice. First, we observed that severe n-3 PUFA deficiency impacts the brain n-3 long-chain PUFA (LCPUFA) composition, yet it was notably mitigated by hepatic de novo synthesis. n-6 LCPUFAs, ether-linked fatty acids, and saturates were also changed by the dietary condition, but the extent of changes was dependent on the genetic background and hormonal condition. Likewise, brain cortex phospholipids were mostly modified by the genotype (FAD>WT) with nuanced effects from dietary treatment. Cholesterol (but not sterol esters) was modified by the genotype (WT>FAD) and dietary condition (higher in DHA-free conditions, especially in WT mice). However, the effects of estrogen treatment were mostly observed in relation to phospholipid remodeling in a genotype-dependent manner. Analyses of lipid-derived variables indicate that nerve cell membrane biophysics were significantly affected by the three factors, with lower membrane microviscosity (higher fluidity) values obtained for FAD animals. In conclusion, our multifactor analyses revealed that the genotype, diet, and estrogen status modulate the lipid phenotype of the frontal cortex, both as independent factors and through their interactions. Altogether, the outcomes point to potential strategies based on dietary and hormonal interventions aimed at stabilizing the brain cortex lipid composition in Alzheimer's disease neuropathology.
Topics: Alzheimer Disease; Animals; Fatty Acids, Omega-3; Mice; Frontal Lobe; Female; Disease Models, Animal; Amyloid beta-Protein Precursor; Estrogens; Mice, Transgenic; Presenilin-1; Lipid Metabolism; Humans
PubMed: 38927745
DOI: 10.3390/genes15060810 -
Cells Jun 2024Microglia activity can drive excessive synaptic loss during the prodromal phase of Alzheimer's disease (AD) and is associated with lowered cyclic adenosine monophosphate...
Microglia activity can drive excessive synaptic loss during the prodromal phase of Alzheimer's disease (AD) and is associated with lowered cyclic adenosine monophosphate (cAMP) due to cAMP phosphodiesterase 4B (PDE4B). This study aimed to investigate whether long-term inhibition of PDE4B by A33 (3 mg/kg/day) can prevent synapse loss and its associated cognitive decline in APPswe/PS1dE9 mice. This model is characterized by a chimeric mouse/human APP with the Swedish mutation and human PSEN1 lacking exon 9 (dE9), both under the control of the mouse prion protein promoter. The effects on cognitive function of prolonged A33 treatment from 20 days to 4 months of age, was assessed at 7-8 months. PDE4B inhibition significantly improved both the working and spatial memory of APPswe/PSdE9 mice after treatment ended. At the cellular level, in vitro inhibition of PDE4B induced microglial filopodia formation, suggesting that regulation of PDE4B activity can counteract microglia activation. Further research is needed to investigate if this could prevent microglia from adopting their 'disease-associated microglia (DAM)' phenotype in vivo. These findings support the possibility that PDE4B is a potential target in combating AD pathology and that early intervention using A33 may be a promising treatment strategy for AD.
Topics: Animals; Cyclic Nucleotide Phosphodiesterases, Type 4; Mice; Mice, Transgenic; Alzheimer Disease; Cognition; Phosphodiesterase 4 Inhibitors; Microglia; Disease Models, Animal; Presenilin-1; Humans; Amyloid beta-Protein Precursor; Male
PubMed: 38920631
DOI: 10.3390/cells13121000 -
Brain Research Jun 2024Abnormally elevated homocysteine (Hcy) is recognized as a biomarker and risk factor for Alzheimer's disease (AD). However, the underlying mechanisms by which Hcy affects...
Folic acid and S-adenosylmethionine reverse Homocysteine-induced Alzheimer's disease-like pathological changes in rat hippocampus by modulating PS1 and PP2A methylation levels.
BACKGROUND
Abnormally elevated homocysteine (Hcy) is recognized as a biomarker and risk factor for Alzheimer's disease (AD). However, the underlying mechanisms by which Hcy affects AD are still unclear.
OBJECTIVES
This study aimed to elucidate the effects and mechanisms by which Hcy affects AD-like pathological changes in the hippocampus through in vivo and in vitro experiments, and to investigate whether folic acid (FA) and S-adenosylmethionine (SAM) supplementation could improve neurodegenerative injuries.
METHODS
In vitro experiments hippocampal neurons of rat were treated with Hcy, FA or SAM for 24 h; while the hyperhomocysteinemia (HHcy) in Wistar rats was established by intraperitoneal injection of Hcy, and FA was added to feed. The expression of β-amyloid (Aβ), phosphorylated tau protein, presenilin 1 (PS1) at the protein level and the activity of protein phosphatase 2A (PP2A) were detected, the immunopositive cells for Aβ and phosphorylated tau protein in the rat hippocampus were also evaluated by immunohistochemical staining.
RESULTS
FA and SAM significantly repressed Hcy-induced AD-like pathological changes in the hippocampus, including the increased tau protein phosphorylation at Ser214, Ser396 and the expression of Aβ In addition, Hcy-induced PS1 expression increased at the protein level and PP2A activity decreased, while FA and SAM were able to retard that.
CONCLUSIONS
The increase in PS1 expression and decrease in PP2A activity may be the mechanisms underlying the Hcy-induced AD-like pathology. FA and SAM significantly repressed the Hcy-induced neurodegenerative injury by modulating PS1 and PP2A methylation levels.
PubMed: 38917878
DOI: 10.1016/j.brainres.2024.149095 -
Journal of Alzheimer's Disease : JAD Jun 2024Presenilin (PSEN, PS) is essential for γ-secretase function, and mutations can disrupt amyloid-β (Aβ) production in familial Alzheimer's disease. Targeting...
BACKGROUND
Presenilin (PSEN, PS) is essential for γ-secretase function, and mutations can disrupt amyloid-β (Aβ) production in familial Alzheimer's disease. Targeting γ-secretase is complex due to its broad involvement in physiological processes.
OBJECTIVE
Our aim was to create a novel knockin (KI) mouse model expressing PSEN1 D385A mutation and investigate the efficacy of a Geniposide and Ginsenoside Rg1 combination (NeuroProtect modified formula, NP-2) in restoring γ-secretase activity.
METHODS
Using gene manipulation, we established the PS1 D385A KI mouse model and confirmed the mutation, mRNA, and protein levels using Southern blotting, northern blotting, and western blotting, respectively. In vitro γ-secretase assay was conducted to measure γ-secretase activity, while histological analyses examined neurogenesis effects. NP-2 administration evaluated its impact on γ-secretase activity.
RESULTS
The PS1 D385A KI homozygotes displayed severe cerebral hemorrhage, postnatal lethality, developmental disorders, reduced proliferation of neural progenitor cells, and disrupted γ-secretase function. The mutation abolished PS1 protein self-shearing, leading to compromised γ-secretase activity. NP-2 intervention effectively restored γ-secretase activity in the heterozygous mice.
CONCLUSIONS
PS1 D385A mutant disrupted PS1 protein self-cleaving, impairing γ-secretase activity in KI mice. NP-2 restored γ-secretase function, offering potential for novel AD treatment strategies despite the challenges posed by γ-secretase's complex role in physiological processes.
PubMed: 38905042
DOI: 10.3233/JAD-231148 -
Biochimica Et Biophysica Acta.... Jun 2024Cancer stem cells (CSCs) are critical for progression, invasion, metastasis, and chemotherapy resistance of pancreatic ductal adenocarcinoma (PDAC). Presenilin enhancer...
Cancer stem cells (CSCs) are critical for progression, invasion, metastasis, and chemotherapy resistance of pancreatic ductal adenocarcinoma (PDAC). Presenilin enhancer 2 (Pen2), a vital component of the gamma-secretase complex, is overexpressed in various cancers and plays a significant role in carcinogenesis. Here, we investigated the association between Pen2 expression and the stem-like properties of PDAC cells. We analyzed Pen2 and its downstream target, Erb-B2 Receptor Tyrosine Kinase 4 (ErbB4), using public databases. The expression of Pen2 in CSC populations, marked by CD133+, CD44+, or epithelial cell adhesion molecule (EpCAM)+, was evaluated. Pen2-positive cells were sorted from Pen2-negative ones in PDAC cells transduced with a vector designed to express green fluorescent protein (GFP) under the Pen2 promoter. Stemness was examined in vitro and in vivo in Pen2-positive versus Pen2-negative cells. Our results showed that Pen2 was significantly upregulated, while ErbB4 was significantly downregulated in PDAC tissues compared to adjacent non-tumorous tissues, with an inverse relationship between Pen2 and Erbb4 levels. PDACs with high Pen2 expression are associated with considerably poorer patient survival. The CSC populations identified by CD133+, CD44+, and EpCAM+ markers displayed significantly higher Pen2 and lower EpCAM levels. Compared to Pen2-negative PDAC cells, Pen2-positive cells formed more tumor spheres, were more invasive and migratory, and showed significantly increased resistance to chemotherapy-induced apoptosis. Altering Pen2 levels reversed these oncogenic effects. In vivo, Pen2-positive cells formed larger tumors in immunodeficient mice. Overall, our findings suggest that Pen2 is highly expressed in CSCs within PDAC cells, being a novel therapeutic target.
PubMed: 38901650
DOI: 10.1016/j.bbadis.2024.167316 -
The New England Journal of Medicine Jun 2024Variants in and (encoding apolipoprotein E and presenilin 1, respectively) alter the risk of Alzheimer's disease. We previously reported a delay of cognitive...
BACKGROUND
Variants in and (encoding apolipoprotein E and presenilin 1, respectively) alter the risk of Alzheimer's disease. We previously reported a delay of cognitive impairment in a person with autosomal dominant Alzheimer's disease caused by the variant who also had two copies of the apolipoprotein E3 Christchurch variant ( ). Heterozygosity for the variant may influence the age at which the onset of cognitive impairment occurs. We assessed this hypothesis in a population in which the variant is prevalent.
METHODS
We analyzed data from 27 participants with one copy of the variant among 1077 carriers of the variant in a kindred from Antioquia, Colombia, to estimate the age at the onset of cognitive impairment and dementia in this group as compared with persons without the variant. Two participants underwent brain imaging, and autopsy was performed in four participants.
RESULTS
Among carriers of who were heterozygous for the variant, the median age at the onset of cognitive impairment was 52 years (95% confidence interval [CI], 51 to 58), in contrast to a matched group of carriers without the variant, among whom the median age at the onset was 47 years (95% CI, 47 to 49). In two participants with the and variants who underwent brain imaging, F-fluorodeoxyglucose positron-emission tomographic (PET) imaging showed relatively preserved metabolic activity in areas typically involved in Alzheimer's disease. In one of these participants, who underwent F-flortaucipir PET imaging, tau findings were limited as compared with persons with in whom cognitive impairment occurred at the typical age in this kindred. Four studies of autopsy material obtained from persons with the and variants showed fewer vascular amyloid pathologic features than were seen in material obtained from persons who had the variant but not the variant.
CONCLUSIONS
Clinical data supported a delayed onset of cognitive impairment in persons who were heterozygous for the variant in a kindred with a high prevalence of autosomal dominant Alzheimer's disease. (Funded by Good Ventures and others.).
Topics: Humans; Alzheimer Disease; Heterozygote; Presenilin-1; Female; Male; Middle Aged; Apolipoprotein E3; Age of Onset; Positron-Emission Tomography; Aged; Brain; Adult; Genes, Dominant; Colombia
PubMed: 38899694
DOI: 10.1056/NEJMoa2308583 -
Gut Jun 2024
PubMed: 38897732
DOI: 10.1136/gutjnl-2024-332677 -
International Journal of Molecular... May 2024Alzheimer's disease (AD) is a devastating disorder with a global prevalence estimated at 55 million people. In clinical studies administering certain anti-beta-amyloid...
Alzheimer's disease (AD) is a devastating disorder with a global prevalence estimated at 55 million people. In clinical studies administering certain anti-beta-amyloid (Aβ) antibodies, amyloid-related imaging abnormalities (ARIAs) have emerged as major adverse events. The frequency of these events is higher among apolipoprotein ε4 allele carriers () compared to non-carriers. To reflect patients most at risk for vascular complications of anti-Aβ immunotherapy, we selected an APPswe/PS1dE9 transgenic mouse model bearing the human gene (APPPS1:E4) and compared it with the same APP/PS1 mouse model bearing the human gene ( ε3 allele; APPPS1:E3). Using histological and biochemical analyses, we characterized mice at three ages: 8, 12, and 16 months. Female and male mice were assayed for general cerebral fibrillar and pyroglutamate (pGlu-3) Aβ deposition, cerebral amyloid angiopathy (CAA), microhemorrhages, apoE and cholesterol composition, astrocytes, microglia, inflammation, lysosomal dysfunction, and neuritic dystrophy. Amyloidosis, lipid deposition, and astrogliosis increased with age in APPPS1:E4 mice, while inflammation did not reveal significant changes with age. In general, carriers showed elevated Aβ, apoE, reactive astrocytes, pro-inflammatory cytokines, microglial response, and neuritic dystrophy compared to carriers at different ages. These results highlight the potential of the APPPS1:E4 mouse model as a valuable tool in investigating the vascular side effects associated with anti-amyloid immunotherapy.
Topics: Animals; Alzheimer Disease; Disease Models, Animal; Mice, Transgenic; Mice; Humans; Female; Male; Amyloid beta-Peptides; Apolipoprotein E4; Presenilin-1; Amyloid beta-Protein Precursor; Cerebral Amyloid Angiopathy; Brain
PubMed: 38891941
DOI: 10.3390/ijms25115754 -
Cell & Bioscience Jun 2024Neural progenitor cells (NPCs) can be cultivated from developing brains, reproducing many of the processes that occur during neural development. They can be isolated...
BACKGROUND
Neural progenitor cells (NPCs) can be cultivated from developing brains, reproducing many of the processes that occur during neural development. They can be isolated from a variety of animal models, such as transgenic mice carrying mutations in amyloid precursor protein (APP) and presenilin 1 and 2 (PSEN 1 and 2), characteristic of familial Alzheimer's disease (fAD). Modulating the development of these cells with inflammation-related peptides, such as bradykinin (BK) and its antagonist HOE-140, enables the understanding of the impact of such molecules in a relevant AD model.
RESULTS
We performed a global gene expression analysis on transgenic neurospheres treated with BK and HOE-140. To validate the microarray data, quantitative real-time reverse-transcription polymerase chain reaction (RT-PCR) was performed on 8 important genes related to the immune response in AD such as CCL12, CCL5, CCL3, C3, CX3CR1, TLR2 and TNF alpha and Iba-1. Furthermore, comparative analysis of the transcriptional profiles was performed between treatments, including gene ontology and reactome enrichment, construction and analysis of protein-protein interaction networks and, finally, comparison of our data with human dataset from AD patients. The treatments affected the expression levels of genes mainly related to microglia-mediated neuroinflammatory responses, with BK promoting an increase in the expression of genes that enrich processes, biological pathways, and cellular components related to immune dysfunction, neurodegeneration and cell cycle. B2 receptor inhibition by HOE-140 resulted in the reduction of AD-related anomalies caused in this system.
CONCLUSIONS
BK is an important immunomodulatory agent and enhances the immunological changes identified in transgenic neurospheres carrying the genetic load of AD. Bradykinin treatments modulate the expression rates of genes related to microglia-mediated neuroinflammation. Inhibiting bradykinin activity in Alzheimer's disease may slow disease progression.
PubMed: 38890712
DOI: 10.1186/s13578-024-01251-3